Flue construction for kilns



March 31, 1931. R. H. YOUNGMAN E1' AL 1,798,297

FLUE CONSTRUCTION FOR KILNS Filed Sept. l2, 1927 3 Sheets-Sheet l lll.

w WITNESSES INVENTORS.

March 3l, 1931. R. H. YOUNGMAN ET Al. 1,798,297

FLUE CONSTRUCTION FOR KILNS Filed Sept. l2, 1927 5 Sheets-Sheet 2 WITNESSES INVENTORS.'

March 31, 1931. R. H. YOUNGMAN E'r Al. 1,798,297

FLUE CONSTHUCTON FOR KILNS Filed Sept. l2, 1927 3 Sheets-Sheet 3 Jag. 3.

WITNESSES INVENTORS:

Patented Mar. 31, 1931 Ntra s f* ROBERT H. YOUNGMAN AND ROBERT H.. H. PIERCE, OF PITTSBURGH, PENNSYLVANIA BLUE coNs'rRUCTio Fon KILNs Application filed September 12, u1927. Serial N'o. 219,136.

The invention relates to kilns and similar structures us'edfor burning ceramic wares, a method of adjusting and controlling the burning operation therein, 'and particularly to a construction of the bottoni and fines thereof.

One object of the. invention is to provide an improved bottom and Hue 'construction iu kilns of the type herein contemplated, which f l0 shall be simple and easily constructed from standard materials, and which is `easily adjustable to vary the effectiveness of the draft exerted on the llues.

A 'specific object of the invention is to produce uniform heating throughout a kiln, by

means of 'a novel bottom and flue construction, which quickly creates a hot bottom condition and equal gas and heat distribution, thereby insuring uniform burning of the Ware.

Another object is to provide an improved bottom and flue construction through the use of Which a wide temperature differential between the top and bottom of the kiln is avoid- 2D ed, and which prevents condensation of moisture on the Ware in the bottom.

Still another object of the invention is to construct the flu'es of such a kiln so that they r are separate from the Walls, thus facilitating repairs to either the walls or the lues.V and rendering cleaning and adjustment of the {iues easier.

Another Objectis t0 control the drawing ofi of the hot gases over substantially the entire area of the kiln floor, around the objects being burned, so as ,to secure uniform operation, the storage of the' hot gas beneath the floor in position to heat it, and the uniform drawing 'off of this stored gas ata speed 40 and at a 'place that will maintain uniformity,

and conserve the heat of the gas.

The accompanying drawings illustrate an ordinary kiln provided With a bottom and flue construction embodying the invention.

5 Fig. 1 is a vertical section through a kiln, showing the bottom and flues; Fig. 2 is a plan view, partly in section, of the kiln shown in Fig, 1;, Fig. 3 is a vertical section on line v IIIe-#III of Fig. 2; Fig. 4 is an enlarged view of a peni-imof the boue-m and une Structure shown in Fig. 3; and Fig. 5 is a plan View of 'a portion of the floor.

The invention is particularly applicable tro 'down-draft kilns, but it is not limit-ed thereto, as it might be applied to 11p-draft kilns. It is particularly diieult to secure uniform heating throughout t-he down-draft periodic l'ilns now in use, and generally there is a wide variation in temperature between the top and bottom thereof during firing. In order to equalize the heat in a kiln it is desirable to have what is termed in the art a hot botto1n; but with kilns of the usual construction the gases pass through the iiring 'chamber and directly to the flu'es and stack and this condition is not readily attained. Also, in these prior kilns, cleaning of the fines is not easy, the damper control is not sufficiently flexible, and in certain types repairing is complicated by integral construction of walls and hues. Furthermore, owing to the lack 'of even heat distribution and eoole'r bottom region, moisture driven ofi' from the Ware in the upper portions may condensefon the Ware in the bottom during the first stages of burning. This causes uneven finish of the charge.

Thepresent invention overcomes all these diiliculties and presents additional advantages which will hereinafter be indicated. It

comprises the use of an ordinary riddle tile bottom permitting draw-olf of hot gas over substantially the entire floor area, of a Hue system consisting of an upper regulating flue therebelow and a lower stack-communicating flue, separated from the upper flue by movable tiles which act as da-inpers and which thus make it possible 'to incre-ase or decrease the resistance to liow of gases from the furnace to the stack. When these damper tiles are properly set to give suiicientl'y restricted and properly distributed openings, a large part of the gases passing through the riddle tiles are forced tochange direction and spread throughout the regulatin"V or ret-arding flues 3' before ei'itering the lower ue. This construction slows up the outflow of gases, and by retaining them in the regulating fines Soniewhat before allowing them to pass to the stack, further opportunity is given fr 'abilo struction of an additional amount of heat, creating the desired hot bottom condition. Another ei ect is to equalize the passage of hot gas through the kiln.

Referring to the drawings, the illustrative embodiment shown comprises a kiln structure composed generally of side walls 1, end walls 2, an arched roof 3, fire boxes 4, a stack 5 and stack bus conduit 6, together with suitable door opening's 7, all providing a burning chamber 8. Peepholes 9 may be provided through the walls for observation of conditions in the chamber, and peepholes 9a for observation of the flues. This structure is built from standard structural and refractory materials as used generally in periodic brick kilns, the details and design being familiar to all those skilled in this art.

In constructing the kiln according to the invention, it is preferably built up from a concrete foundation. In order to protect this foundation from the action of the hot gases and to increase the thermal efciency of the kiln, a refractory and insulating covering is laid on the foundation below the chamber. A satisfactory construction has been found to comprise three courses of fire brick 11 laid on concrete base 10, followed by a layer of insulating brick 12, on which is laid a top course of highly refractory brick 13.

According to the invention, the flue system comprises upper collecting and regulating flues or retarding spaces (20) directly be neath the floor of the chamber, and communicating with lower draft ordraw-off Hues 19) which open into the stack bus.` conduit. This structure is preferably built up by erecting a plurality of walls or piers 14 longitudinally of the kiln, each continuous throughout its length, and extending to stack conduit 6 at one end, thus providing a plurality of channels 15, the sides of which form the Walls of the upper and lower ues. Similar piers 14a are provided in the bays formed between the fire boxes, the cross channels thus formed opening into the adjacent longitudinal channels.

The construction of these piers is shown on an enlarged scale in Fig. 4. They may be builtfrom suitable brick capable of Withstanding the action of the hot gases, and arc built up to form the lower flues, to a height sulicient to properly carry off the waste gases, this being usually adjusted to the area of the stack conduit 6. At this point two successively wider projecting courses, 16 land 17 are laid, bricks 17 forming supporting shelves on each side of each column, followed by smaller brick again, and finally a top course consisting of an inverted T-shape brick. The extended edges of bricks 17' provide ledges upon which are freely laid flat tiles 18, thus dividing channels 15 into lower stackcommunicating flues 19 and upper regulating flues 20. The floor of the kiln consists of riddle tiles 21 positioned between the tops of columns 14 and having their upper sides flush with the column tops. These tiles are rectangular and have on one side vertical lugs 22, so that when they are laid side by side in contact there is a space between them for passage of the gases into the upper flues. These riddle tiles rest on the shoulders of the inverted T-brick forming the tops of the piers, as shown in Figs. 4 and 5.

The tiles 18 rest freelyY on the projections 17 from the flue walls and they may be moved closer together or farther apart, in order to decrease or to increase the size of opening between the upper and lower fiues, and for this reason they maybe conveniently referred to as draft-regulating or damper tiles. In general the total opening between the riddle tiles will be considerably-T in excess of that necessary, and the flow of gases is governed, not by the riddle openings in the floor, but by theopenings between the damper tile beneath flues 20. lDampers 23 may also be set in the ends of the lower draft flues 19, in

order to regulate draw-off to the stack during burning.

In operation of the kiln the Ware is stacked on the kiln floor in the usual manner, and after sealing off the doors and other openings, firing is commenced. The hot gases pass upwardly from the fire boxes into the kiln and are deflected from the roof uniformly through the ware, passing into the regulating lues 2O through the riddle openings. In order to pass into the lower flues 19, the gases must spread and flow through the regulating liues 20 until they reach the openings between the damper tile, when they move down into the lower liues and out into the stack.

This constructionl has two main effects. First, the use'of the damper tiles 18 retards flow of the waste gases from'the kiln, and by holding the gas under the floor, a hot bottom condition is quickly created. Due to this retardation of gas removal resulting in more uniform draw-off over the entire floor area, better diffusion in the kiln itself is secured. Both these factors combined to secure greater efficiency. and the result is that thel kiln quickly reaches a uniform condition of temperature distribution, which does not vary greatly from top to bottom, and moisture condensation on the bottom ware is substantially avoided. Actualpractice' with a kiln constructed according to the invention has deraonstrated that the temperature in the ware chamber is remarkably uniform, all parts being within 1 or 2 cones, and temperature in the regulating flue is about 6 cones below that in the ware chamber.

This flue system may be applied to old kilns, by rebuilding the bottom and adapt- -ing the stack outlet to receive the lower fines.

It is likewise applicable to other types of kilns, such. as square or round, without any invention does not include the chamber or iwall structure, it is unnecessary to illustrate Athose forms.

'In general lt is preferred to fire with gas, but any other suitable fuel, such as oil or coal, may be used.

Thus the invention provides a readily constructed kiln bottom and llue system, applicable to both new and old'structures, which is easily adjustable to closely regulate the burning operation so as to secure close uniformity of heat distribution in the kiln, to keep the moisture driven from the ware above the condensation point, and to overcome the other disadvantages of the kiln flue systems heretofore used. The uniform heating secured in kilns constructed according to the invention especially adapts them for burning wares at very high temperatures. The

rapid and uniform heat distribution secured by the practice of the invention insures considerable heat economy, because more of the heat supplied to the kiln is utilized in the burning than has been the case with prior constructions, and forcing the kiln to equalize burning in the later stages is rendered unnecessary, because all the ware burns uniformly in the new kiln. Furthermore, the high heat absorption in the burning chamber reduces the temperature in the lower iues and in the stack, and this in turn increasesA the life of the flues and stack. The life of the kiln chamber itself is also increased, inasmuch as the uniform heating produced eliminates local overheating with its consequent rapid deteriorating action. Furthermore, the individual damper tile and riddle tile remain loose and are easily removable and replaceable for cleaning of the flues whenever this may be necessary.

The invention is not narrowly limited to the structure vdisclosed herein, as this is given merely for purpose of illustration, and variations falling within the scope of the invention and securing the desired uniform heat distribution and controlled gas flow are within the skill of those familiar with thisI art.

We claim:

l. The combination in a kiln for firing ceramic ware, of a floor comprising riddle tiles supported on a plurality of intermediate piers, the sides of said piers forming the walls of a flue system comprising upper regulating lues disposed below the floor and lower stack-communicating flues, said upper and lower flues being separated by tiles adjustably disposed therebetween and adapted to act as dampers to cause the waste gases to spread through and be retarded in the regulating flues below the floor before passing to the stack flues.

`Athe kiln, comprising a 2. Afluesystem for use with kilns adapted to avoid a wide temperature differential in plurality of channels disposed beneath the floor of a kiln, each divided into upper regulating flues andflower stacli-communicating lines by damper tiles disposed in said channels, said'ftilesbeing adjustable to vary the openings therebetween, whereby to govern the flow of gases fromthe kiln and to cause the waste gasesto spread through 'the upper flue and uniformly heat the floor of the kiln.

3. A kiln having fire-boxes and an exhaust stack for burning bricks and like products, comprising a floor structure made up =of a,l series of transverse ypiers leading to a bus stack flue atoneend, riddle tiles supported on and between said piers and completing the floor surface and providing outlets between adjacent tiles for escape of gases ofl combustion, damper tiles dividing horizontally the space between said piers a material distance below said riddle tiles whereby yto form retarding spacesor flues just beneath the riddle tiles, said damper tiles Abeing slidably supported by ledges formed onthe sides of the piers, the space below said 'damper tiles forming secondary retarding llues connected to a stack flue, and adjustable dampers controlling said secondary flues at their connection tothe stack iue.

4. The combination with a kiln for :firing ceramic wares, of a floor adapted for passage of the waste gases. a plurality of lines lisposed beneath said floor, and adjustable means provided between said tlues for retarding the passage of'the gases therebetween and to cause them to spread out beneath the floor. whereby the ware in the k-iln is uniformly heated throughout.

5. A kiln having fire boxes andan exhaust stack for burning bricks and like products, comprising a fioor structure madeupof aseries of transverse piers forming passages leading to a bus stack flue at one=end, riddh` tiles supported on and bet-Ween said ipiers completing the door surface 'therebetween and providing outlets therethrough for lescape of gases of combustion, damper tiles-drividing horizontally the space between said piers below said riddle tiles, said dampcrtiles being slidably mounted, the space bdlow said damper tiles forming secondary flues connected to the stack flue, and adjustabledampers controlling said secondary lines at their connection tothe stack flue.

6. A kiln comprising fire boxesand an eX- haust stack for burning bricks and Alike products, comprising a floor structure anade up of a series of transverse piers forming passages leading to a bus stack flue 'at-onelend. riddle tilescompleting the floor surfacerabove said passages and providing outlets `there through for escape of gases of combustion. slidablyfmounted dampertiles dividing'horibetween said piers below said riddle tiles, the spaces below said damper tiles forming secondary flues connected to the stack flue, and adjustable dampers controlling said secondary flues at their connection to the stack flue.

7. A kiln for burning bricks and like products having a floor structure made up of a series of transverse piers leading to a bus stack flue at onel end, riddle tiles completing the floor surface between said piers and providing outlets therethrough for escape of gases of combustoin, adjustable dampers horizontally dividing the space between said piers below said riddle tiles, said dampers being adapted to control flow of gas from the kiln, the space below said dampers forming secondary iiues and being connected to the stack flue, and adjustable dampers controlling said secondary flues at their connection to the stack flue, whereby to regulate draw-olf of gases through the kiln floor, and to hold hot gas in the floor structure.

8. A kiln for firing ceramic ware comprising walls, a roof,liringboxes,arefractory base for said kiln, a plurality of heat resisting piers erected on said base and forming channels through it, ledges formed on said piers, damper tiles slidab-ly resting on said ledges and dividing said channels into upper and lower lues, stack connections to said lower Hues, and a floor comprising riddle tiles hav- Iing projections on the sides thereof to provide gas passages therebetween supported on being adjustable to control the openings therebetween, whereby to cause the waste gases to spread under and be retaining in heating relation to the floor.

9. The combination with a kiln for firing ceramic wares, of a floor adapted to permit passage of hot gases therethrough throughout its area, lues beneath the floor for collecting said gas, draw-off lues below said first mentioned 'lues, and movable means positioned between said upper and lower fines whereby the flow of gases from the upper filles to the lower flues may be regulated as to rate and place.

10. The combination with a kiln of the class described, of a floor adapted to permit down-How of gas throughout its area, collecting llues beneath said floors adapted to store hot gases below the floor, exhaust lues under the floor and co-extensive with the said collecting Hues, and movable means between said collecting and exhaust llues adapted to control the rate and place of flow of gas theretween.

11. In a kiln of the class described, the combination of a Hoor perforated to permit down-flow of gas throughout its area, collecting and regulating iues beneath the floor adapted to receive and store the hot gases under the Hoor, parallel co-extensive drawzontallv the space whereof, we hereunto sign 

